1. Field of the Invention:
This invention relates to a method and apparatus for compressing hydrogen gas and, more specifically, to such a method and apparatus which employs one or more hydride reservoirs operably connected to a heat pump for compressing the hydrogen gas.
2. Description of the Prior Art:
German Patent Publication Published for Opposition Purposes No. 26 41 487 discloses a process for the compression of hydrogen gas using a hydride reservoir, in which the hydrogen gas is initially introduced into the hydride reservoir under low pressure. The heat (binding enthalpy) released by the ensuing hydride formation (hydrogenation phase) is continuously removed from the hydride reservoir by means of a coolant. After the maximum reservoir discharge is achieved, the hydride reservoir is heated so that the hydrides formed begin to decompose again (dehydrogenation phase), and the hydrogen gas pressure in the hydride reservoir increases to a maximum (equilibrium pressure). The compressed hydrogen produced in accordance with the above-referenced patent is used to operate a flash gas turbine to produce electrical energy, and circulates in a closed circuit. To heat the hydride reservoir, the flow of a heating medium at a temperature of less than 232 degrees C. is used. The application of the prior art assumes that the fluid flows for the cooling and heating medium are automatically available and cannot be efficiently used in any other manner.
The prior art also includes the operation of hydride reservoirs merely for the purpose of hydrogen compression. If there are particular requirements for the purity of the hydrogen gas, impurities which are caused by the presence of lubricants in mechanical compressors can thereby be prevented.
The required coolant flow (heat sink) for the hydrogenation phase can, as a rule, be relatively economically provided in the form of surface or well water. However, the supply of the heating medium flow (heat source) for the dehydrogenation phase, in the form of primary energy or electrical energy, is generally more expensive, since it cannot be automatically assumed that an appropriate source of waste heat, for example, will be available free of cost, As a rule, therefore, a conventional heating unit (instantaneous water heater) is used to produce hot water. In addition to the energy expense, this process also involves expenses for water treatment.